Stacked plate visual display panel

ABSTRACT

An electroluminescent display device comprising an assembly of stacked transparent dielectric plates, in which every other plate includes a channel forming a cell having a particular character configuration. Each cell is insulated from every other cell, and each contains an electroluminescent material. A transparent film electrode is deposited on the front surface of the plate assembly in such a manner that the film electrode overlies every character configuration in the assembly. A plurality of electrodes is deposited on the rear exterior surface of the assembly, each electrode corresponding to one particular character and overlying only a portion of the character to which it corresponds. A particular character in the stacked assembly is displayed by alternately energizing the film electrode and the electrode corresponding to the desired character. Only that character which is positioned between the film electrode and the selected character electrode will be affected by the alternating field because of the capacitive coupling effect which exists between the character electrode and the selected character cell and because of the capacitive coupling effect which exists between the film electrode and the selected character cell.

United States Patent [72] Inventor John L. Janning Dayton, Ohio [211 App]. No. 879,125 [22] Filed Nov. 24, 1969 [45] Patented Nov. 16, 1971 [73] Assignee The National Cash Register Company Dayton, 01110 [54] STACKED PLATE VISUAL DlSPLAY PANEL 17 Claims, 9 Drawing Figs.

[52] 0.8. CI. 315/313, 313/109.5, 313/201, 313/220, 340/343 [51] Int. Cl. 1105b 41/00 [50] FleldoiSearch 3l3/l09.5. 108 A, 108 R; 315/169 R, 169 TY, 313; 340/336, 343, 344

[56] References Cited UNITED STATESPATENTS 3,127,535 3/1964 Westerheim 313/1095 3,500,390 3/ 1970 McNaney et a1 340/336 X Primary Examiner-Raymond F. Hossfeld Attorneys-Louis A. Kline and Albert L. Sessler, Jr.

ABSTRACT: An electroluminescent display device comprising an assembly of stacked transparent dielectric plates, in which every other plate includes a channel forming a cell having a particular character configuration. Each cell is insulated from every other cell, and each contains an electroluminescent material. A transparent film electrode is deposited on the front surface of the plate assembly in such a manner that the film electrode overlies every character configuration in the assembly. A plurality of electrodes is deposited on the rear exterior surface of the assembly, each electrode corresponding to one particular character and overlying only a portion of the character to which it corresponds. A particular character in the stacked assembly is displayed by alternately energizing the film electrode and the electrode corresponding to the desired.character. Only that character which is positioned between the film electrode and the selected character electrode will be affected by the alternating field because of the capacitive coupling effect which exists between the character electrode and the selected character cell and because of the capacitive coupling effect which exists between the film electrode and the selected character cell.

PATENTEBunv 16 um SHEET 1 OF 2 INVENTOR! JOHN L. JANNI Wm M BY WM W7 HIS ATTORNEYS FATENTEDuuv 1s 19?:

SHEET 2 OF 2 BY wimw HIS ATTORNEYS STACKED PLATE VISUAL DISPLAY PANEL BACKGROUND OF THE INVENTION This invention relates to an electroluminescent display device.

Electroluminescent display devices which produce a glow upon the application of an electric field across a cell containing an electroluminescent material are well known. Devices of this type are exemplified in U.S. Pat. No. 3,127,535, issued Mar. 31, 1964, on the application of Harold T. Westerheim, U.S. Pat. No. 3,353,050, issued Nov. 14, 1967, on the application of Maria Panerai et al., U.S. Pat. No. 3,376,454, issued Apr. 2, 1968, on the application of Elmer 0. Stone, and British Pats. Nos. 1,161,832 and 1,161,833.

A continuing problem, common to most electroluminescent devices, is the inability to provide a structure which has small physical dimensions and which is capable of easy fabrication. Another problem is the inability to illuminate a character in a stacked assembly which is not obscured by characters which might precede it, sometimes known as "shadowing." Many of the prior art devices incorporate the energizing electrodes within the device itself, which also causes shadowing. Also, the electrodes are subject to rapid deterioration because of placement within the display cell, a problem which applicant's structure does not experience.

The instant invention provides a display device in which shadowing is eliminated and also provides a structure which, because of its simplicity, is capable of easy manufacture. It further provides a display system capable of being operated with an alternating source of potential.

SUMMARY OF THE INVENTION The invention relates to an electroluminescent display panel composed of an assembly of stacked transparent dielectric plates in which every other plate positioned between the front and rear sides has a channel cut thcrethrough, the channel conforming to a particular character, which may be a letter, a numeral, or a symbol. The channels are buttressed on each side by insulating plates, thus forming a plurality of discharge cells, each in the shape of a particular character. The front side of the assembly has a transparent film electrode deposit such that the film electrode overlies every character cell in the assembly and is therefore capacitively coupled to each cell in the assembly because of the glass dielectric which separates the electrode from the cells. A plurality of character electrodes are located on the rear surface of the assembly, each electrode corresponding to one cell and so positioned that each individual electrode overlies only a portion of the cell to which it corresponds. The character electrodes are also capacitively coupled to their corresponding characters-i.e., cells-because of the glass dielectric interposed between each electrode and its respective cell.

The illumination necessary for viewing is provided by the application of an alternating electric field across a selected cell, which results in the ionization of a gas within the selected cell. The alternating electric field causes an electron multiplication process to occur within the selected cell, which con tinues until ignition occurs--i.e., a gaseous discharge occurs within the selected cell-thus providing the necessary illumination for the display of the selected character. The gas discharge also results in the deposit of a positive charge on the cell wall which is capacitively coupled to the electrode to which the negative potential is being applied, and causes electrons to be deposited on the cell wall which is capacitively coupled to the electrode to which a positive potential is being applied. The charges deposited on the inner cell wall surfaces are known as wall charges and are trapped on the cell walls because of the capacitive coupling effect exerted by the cell walls. The wall charge gives rise to a wall voltage which has a polarity opposite to the polarity of the applied voltage which initiated the discharge. The reverse cycle of the alternating potential results in the application of a voltage to the common film electrode and to the selected character electrode which is now of the same polarity as the wall voltage, and therefore the two are additive. Consequently it can be seen that after the first ignition, less voltage is required to fire the cells; in other words, the voltage necessary to ignite the selected cell after the first ignition can be of a magnitude which is equal to the original firing voltage less the wall charge. The selected character will remain illuminated for so long as the alternating electric field is applied to the respective electrodes which are capacitively coupled to the cell representing the selected character.

In a second embodiment of the invention, a plurality of characters are provided on each plate, thus providing a display panel capable of simultaneously displaying a plurality of characters.

In further disclosed embodiments of the invention, single or multiple cells defining characters are formed on each plate by etching a character design on one side or both sides of adjacent plates.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an exploded isometric view of the display assembly in accordance with the invention.

FIG. 2 is a front view of one type of character plate mounted on an insulating member having a plurality of air passages scribed on the insulating plate surface.

FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG. 2.

FIG. 4 is a front view of another type of character plate that may be used in the present invention, in which the character is connected to a conduit by means of a channel.

FIG. 5 is a schematic view showing one form of control arrangement employed with the display assembly of FIG. 1.

FIG. 6 is an isometric view of another form of the invention embodying the principles of the instant invention.

FIG. 7 is an exploded isometric view of yet another form of the invention.

FIG. 8 is an exploded isometric view of another form of the invention.

FIG. 9 is an enlarged view, partly in cross section, taken along the line 9-9 of a type of character plate used in FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, a visual display assembly, composed of glass dielectric plates, is shown generally at 20. The assembly consists of an exterior front plate 21 followed by character plates 22, 24, and 26. Each character plate is separated and isolated from the other character plates by transparent flat plates 23, 25. The assembly is terminated in a flat plate 27. The character plates contain character cells formed by channels cut therethrough in the configuration of a particular character, thereby limiting each character plate to the configuration of the channel cut through the plate. A variety of information may be displayed utilizing this type of assembly simply by changing the physical shapes of the channels which are cut through the character plates. It will be understood that while only three characters are shown in theembodiment of FIG. 1, the invention is not limited to any particular number of characters. For purposes of illustration, four characters are shown in FIG. 5.

The front surface of the plate 21 is coated with a conductive transparent film electrode 28, which overlies each and every character cell in the display assembly. The film electrode 28 may be tin oxide, cadmium oxide, or a thin gold film deposit, and may be deposited by conventional methods such as metal deposition techniques. Character electrodes 32, 34, and 36 are similarly deposited on the exterior side of the rear plate 27, in such a manner that each character electrode overlies only a portion of that character cell to which it corresponds. In other words, if each character electrode were to be extended through the entire assembly, it would intersect only the character to which it corresponds, and no other.

The film electrode 28 is capacitively coupled to every character cell in the assembly because of the glass dielectric plates separating the electrode from the cells. Similarly, the character electrodes 32, 34, and 36 are capacitively coupled to only their respective characters.

Each plate, except the front plate 21, in the assembly illustrated in FIG. 1 has a hole 29 cut through it. These holes in the completed assembly 20 form a common passageway. A conduit 30 is shown connected to the rear plate 27, the conduit 30 being in communication with the common passageway formed by the hole 29 in the assembly. Although the conduit 30 is shown on the rear plate, it may be placed with equal facility on the front plate. The conduit 30 and the cooperating holes 29 in the succeeding plates are used to evacuate the completed assembly of any air that may be in the character cells. The conduit is also utilized to introduce an electroluminescent material-i.e., gasinto the respective display assembly character cells.

Various modifications may be made in the assembly in order to facilitate the outgasing of the air. For example, FIG. 2 illustrates a plurality of passages 31 forming a grid network on the insulating plate 27, which is adjacent to the plate containing the character 3." These passages communicate with the hole in that plate, thereby providing a plurality of paths for evacuating the cells of any air which they may have and for introducing a gas therein. FIG. 4 shows yet another method of connecting the character to the hole. This is shown as one passageway 33 connected to the character cell and to the hole 29 on the character plate. Still another method which may be utilized is to immerse the plates in a hydrofluoric acid solution for a fraction of a second in order to provide an uneven surface on the plate, which provides a plurality of irregular passages (not shown) through which air can pass, into the holes 29 and out of the conduit 30. Yet another method which may be utilized is simply to rely on the natural imperfections of the adjoining surfaces of adjacent glass plates, which may provide sufficient paths for evacuation of air and introduction of a suitable gas. The completed assembly may be sealed with any conventional means such as glass frit or glass cement, thereby resulting in an airtight structure.

FIG. 5 discloses an AC source 37 connected to a plurality of parallel switches 38, 39, 40, and 41. These switches in turn are connected to their respective character electrodes, located on the rear surface of the rear plate 27. Four characters are shown in FIG. 5 in order to illustrate the fact that the assembly 20 is expandable. The transparent film electrode 28 is shown connected to the return of the AC source.

In operation, the display performs as follows: closing the switch 38 causes the application of an electric field between the electrode 36 and the common transparent electrode 28. The magnitude of the initial energizing pulse must be sufficient to initiate an electron multiplication process to occur at that portion of the character cell coupled to the electrodes 28 and 36. This phenomenon spreads throughout the entire cell until breakdown occurs; i.e., a gaseous discharge occurs within the cell forming the character 3. Ionization will take place only in the cell located on the plate 26, because the electrode 36 is capacitively coupled only to that cell and because each cell is isolated from the others. Therefore, energization of the electrode 36 does not affect any of the characters that are not in direct line with the energized electrode. The ionization occurring within the channel also results in the deposition of a wall charge on the inner surfaces formed by the external plates; in this case, the plates 25 and 27. The wall charges are formed by a positive charge being deposited on the character cell wall which is capacitively coupled to the electrode to which negative potential is being applied and by electrons being deposited on the character cell wall capacitively coupled to the electrode to which a positive potential is being applied. These charges are trapped on the cell walls because of the capacitive-coupling effect exerted by the glass cell walls. Each deposited wall charge gives rise to a wall voltage which has a polarity opposite to that of the applied voltage which initiated the ignition of the gas. The next cycle, because of its reverse polarity, results in the application of a field to the selected electrodes which is now of the same polarity as the previously deposited wall charges, and therefore the two are additive. Consequently, it can be seen that, after the first ignition, less voltage is required to sustain further ignitions. In other words, the firing voltage after the first ignition can be of a magnitude which is equal to the original firing voltage less the wall voltage contributed by the wall charges.

Referring to FIG. 6, a second embodiment encompassing the principles of the invention is shown generally at 120. The construction of this assembly is similar to that of FIG. I with one major exception, which is that a plurality of characters is shown on each plate, thereby allowing the illumination of a multicharacter display. Transparent electrodes 128 and 228 are deposited on the front surface of the assembly 120, one transparent electrode for each such group of character cells in front-to-back registry.

A plurality of character electrodes, not shown, is deposited on the exterior rear surface of the assembly 120, one electrode for each character cell. The operation of the assembly 120 is similar to that of the assembly 20, shown in FIG. 1, except that two characters are being displayed simultaneously rather than just one.

The stacked assembly 59 of adjacent plates illustrated in FIG. 7 consists of a front plate 60 followed by plates 61, 62, and 63, each having first and second opposed sides. Channels etched on one side of each plate fonn the character cells in the assembled structure. The channels are etched by the use of conventional etching techniques. It can be seen that the cell formed on the first side of each plate, excluding the first side of the plate 60 (i.e., the exterior side), is the mirror image of the cell formed on the second side of an adjacent plate and will be in full registration with said other cell when assembled. Assembly of the plates in front-to-back registry results in a plurality of cells, each conforming to the shape of a particular character. A common transparent electrode 64 is positioned on the exterior surface (first side) of the plate 60, and a plurality of character electrodes 69, 70, 71, 72, and 73 are positioned on the exterior surface (second side) of the plate 63, each character electrode corresponding to one character; i.e., the two decimal points and the numerals l, 2, and 3. An electroluminescent gas is introduced into each character cell. The operation of this display is similar to that described for the embodiment of FIG. 1.

Although FIG. 7 illustrates cells formed by channels etched on the first and second sides of each plate positioned between the two exterior surfaces of each plate, the invention is not limited to this structure, since cells could be formed by channels etched on one side of every plate, excluding, of course, '1

the exterior surfaces of the plates 60 and 63.

FIG. 8 illustrates a stacked assembly 75 of adjacent plates comprising a front plate 76, and character plates 77 and 79, which are separated by an insulating plate 78. Channels are etched on each side of the plates 77 and 79, each channel forming a particular character cell. A plate 80 terminates the assembly, which is assembled into an airtight structure, as illustrated in FIG. 6. Electrodes 81, 82, 83, and 84 are deposited on the exterior surface (second side) of the plate 80. The electrodes correspond to only one character cell. A transparent electrode 85 is deposited on the exterior surface (first side) of the plate 76. The operation of this display is similar to that described for the embodiment of FIG. 1.

It can be seen that the electroluminescent display assemblies disclosed according to the instant invention result in a very similar structure capable of easy manufacture yet providing maximum illumination without any accompanying shadowing effects. These assemblies can be utilized to display numbers, alphabetic characters, alpha-numeric characters, symbols, or a combination of all of these without any complex circuitry or complex physical structure.

In order to aid those skilled in the art in the practice of the present invention, the following information for construction of one form of the display device is given by way of exemplification only. in the embodiment illustrated in FIG. l, the character channels were cut through plates having a thickness of 0.010". The insulating plates were also of the same thickness. The channels were filled with a gas mixture of neon and argon to a pressure of to 30 millimeters of mercury at room temperature. The energizing voltage had a magnitude of 2,000 volts AC at kill. it was found that, if desired, the addition of nitrogen to the gas mixture increased the wall charge, or memory, experienced by the display symbol channel walls.

What is claimed is:

1. An electroluminescent display device, comprising:

an assembly of stacked transparent plates, each plate having first and second opposed sides, and said assembly having exterior front and rear surfaces, certain of said plates including at least one channel forming a character cell conforming to a particular character, said cells positioned in front-to-back registry;

an excitable gas filling said character cells;

a transparent film electrode positioned on the front surface of said assembly, such that said film electrode overlies the character cells; and

a plurality of character electrodes positioned on the rear surface of said assembly, each electrode corresponding to one character cell and each positioned so that each electrode overlies only a portion of its corresponding character cell.

2. A device in accordance character cell in said assembly conduit for the introduction of character cells.

3. A device in accordance with claim 2 wherein means are provided for alternately energizing a selected film electrode and a selected character electrode for the ignition of the gas in the cell coupled to the energized electrodes.

4. A device in accordance with claim 3 wherein every other plate positioned between the front and rear surfaces has a channel forming a character cell extending therethrough.

5. A device in accordance with claim 3 wherein the first side of every plate positioned between the front and rear exterior surfaces has a channel forming a character cell formed thereon.

6. A device in accordance with claim 5 wherein the second side of every plate positioned between the front and rear exterior surfaces has a channel forming a character cell etched thereon, the channel being the mirror image of and in full registration with a channel formed on the first side of an adjacent plate.

7. A device in accordance with claim 3 wherein the second side of every plate positioned between the front and rear exterior surfaces has a channel forming a character cell formed thereon.

8. A device in accordance with claim 3 wherein the first and second opposing sides of every other plate positioned between the front and rear surfaces have a channel forming a character cell formed thereon, said plates including cells separated from each other by a separating plate.

9. An electroluminescent device for of characters, comprising;

an assembly of stacked transparent dielectric plates, said assembly having a front and a rear exterior surface, in which every other plate positioned between the front and rear exterior surfaces has a plurality of channels cut through it, said channels forming character cells conforming to particular characters and so arranged that the cells of the various plates are positioned in groups in front-to-back registry in the assembly;

an electroluminescent material in said character cells;

a plurality of transparent film electrodes positioned on the with claim 1 wherein every is in communication with a said excitable gas into said illuminating a plurality front surface of the assembly, so that each film electrode overlies a group of character cells of the assembly; and a plurality of character electrodes, positioned on the rear surface of said assembly, each electrode corresponding to one character cell and so positioned that each character electrode overlies only a portion of its corresponding character cell.

10. A device in accordance with claim 9 in the assembly is in communication with a one passageway for the introduction mineecent material into said cells.

ii. A device in accordance with claim 110, further comprising means for alternately energizing selected ones of said film electrodes and selected ones of said character electrodes for producing an illuminated display in each group conforming to the shape of the character corresponding to the selected character electrode.

12. An electroluminescent display device for illuminating a character, comprising:

an assembly of stacked transparent plates, said assembly having a front and a rear surface, in which every other plate positioned between the front and rear surfaces includes a channel forming character cell confonning to a particular character;

an electroluminescent material in said character cells;

a transparent film electrode positioned on the front surface of the assembly, so that the film electrode overlies every character cell in the assembly; and

a plurality of character electrodes positioned on the rear surface of said assembly, each character electrode corresponding to a particular character cell and positioned so that each electrode overlies only a portion of its corresponding character cell.

13. A device in accordance with claim 12 in which every cell in the assembly is in communication with a conduit by at least one passageway for the introduction of said electroluminescent material into said cells.

M. A device in accordance with claim ing means for alternately energizing the film electrode and a selected one of said character electrodes for producing an illuminated display conforming to the shape of the character cell corresponding to the selected character electrode.

l5. An electroluminescent display device for illuminating a character, comprising:

an assembly of stacked adjacent transparent plates, terminating at each end with a flat exterior surface, each plate having first and second opposed sides, in which at least one side of every plate has a channel etched thereon, said channel fonning a character cell conforming to a particular character;

an electroluminescent gas filling said character cells;

a transparent film electrode positioned on one of the exterior surfaces, so that the film electrode overlies every character cell in the assembly; and

a plurality of character electrodes positioned on the other exterior surface, each character electrode corresponding to one cell and so positioned that each electrode overlies only a portion of its corresponding cell.

16. A device in accordance with claim 15, further comprising means for alternately energizing the film electrode and a selected one of said character electrodes for producing an illuminated display conforming to the shape of the character corresponding to the selected character electrode.

17. A device in accordance with claim 16 wherein every said side positioned between the two exterior flat assembly surfaces also has a channel etched thereon, the channel being the mirror image of and in full registration with the channel etched on the adjacent side of an adjacent plate.

in which every cell conduit by at least of said electrolul3, further compris- 

1. An electroluminescent display device, comprising: an assembly of stacked transparent plates, each plate having first and second opposed sides, and said assembly having exterior front and rear surfaces, certain of said plates including at least one channel forming a character cell conforming to a particular character, said cells positioned in front-to-back registry; an excitable gas filling said character cells; a transparent film electrode positioned on the front surface of said assembly, such that said film electrode overlies the character cells; and a plurality of character electrodes positioned on the rear surface of said assembly, each electrode corresponding to one character cell and each positioned so that each electrode overlies only a portion of its corresponding character cell.
 2. A device in accordance with claim 1 wherein every character cell in said assembly is in communication with a conduit for the introduction of said excitable gas into said character cells.
 3. A device in accordance with claim 2 wherein means are provided for alternately energizing a selected film electrode and a selected character electrode for the ignition of the gas in the cell coupled to the energized electrodes.
 4. A device in accordance with claim 3 wherein every other plate positioned between the front and rear surfaces has a channel forming a character cell extending therethrough.
 5. A device in accordance with claim 3 wherein the first side of every plate positioned between the front and rear exterior surfaces has a channel forming a character cell formed thereon.
 6. A device in accordance with claim 5 wherein the second side of every plate positioned between the front and rear exterior surfaces has a channel forming a character cell etched thereon, the channel being the mirror image of and in full registration with a channel formed on the first side of an adjacent plate.
 7. A device in accordance with claim 3 wherein the second side of every plate positioned between the front and rear exterior surfaces has a channel forming a character cell formed thereon.
 8. A device in accordance with claim 3 wherein the first and second opposing sides of every other plate positioned between the front and rear surfaces have a channel forming a character cell formed thereon, said plates including cells separated from each other by a separating plate.
 9. An electroluminescent device for illuminating a plurality of characters, comprising; an assembly of stacked transparent dielectric plates, said assembly having a front and a rear exterior surface, in which every other plate positioned between the front and rear exterior surfaces has a plurality of channels cut through it, said channels forming character cells conforming to particular characters and so arranged that the cells of the various plates are positioned in groups in front-to-back registry in the assembly; an electroluminescent material in said character cells; a plurality of transparent film electrodes positioned on the front surface of the assembly, so that each film electrode overlies a group of character cells of the assembly; and a plurality of character electrodes, positioned on the rear surface of said assembly, each electrode corresponding to one character cell and so positioned that each character electrode overlies only a portion of its corresponding character cell.
 10. A device in accordance with claim 9 in which every cell in the assembly is in communication with a conduit by at least one passageway for the introduction of said electroluminescent material into said cells.
 11. A device in accordance with claim 10, further comprising means for alternately energizing selected ones of said film electrodes and selected ones of said character electrodes for producing an illuminated display in each group conforming to the shape of the character corresponding to the selected character electrode.
 12. An electroluminescent display device for illuminating a character, comprising: an assembly of stacked transparent plates, said assembly having a front and a rear surface, in which every other plate positioned between the front and rear surfaces includes a channel forming character cell conforming to a particular character; an electroluminescent material in said character cells; a transparent film electrode positioned on the front surface of the assembly, so that the film electrode overlies every character cell in the assembly; and a plurality of character electrodes positioned on the rear surface of said assembly, each character electrode corresponding to a particular character cell and positioned so that each electRode overlies only a portion of its corresponding character cell.
 13. A device in accordance with claim 12 in which every cell in the assembly is in communication with a conduit by at least one passageway for the introduction of said electroluminescent material into said cells.
 14. A device in accordance with claim 13, further comprising means for alternately energizing the film electrode and a selected one of said character electrodes for producing an illuminated display conforming to the shape of the character cell corresponding to the selected character electrode.
 15. An electroluminescent display device for illuminating a character, comprising: an assembly of stacked adjacent transparent plates, terminating at each end with a flat exterior surface, each plate having first and second opposed sides, in which at least one side of every plate has a channel etched thereon, said channel forming a character cell conforming to a particular character; an electroluminescent gas filling said character cells; a transparent film electrode positioned on one of the exterior surfaces, so that the film electrode overlies every character cell in the assembly; and a plurality of character electrodes positioned on the other exterior surface, each character electrode corresponding to one cell and so positioned that each electrode overlies only a portion of its corresponding cell.
 16. A device in accordance with claim 15, further comprising means for alternately energizing the film electrode and a selected one of said character electrodes for producing an illuminated display conforming to the shape of the character corresponding to the selected character electrode.
 17. A device in accordance with claim 16 wherein every said side positioned between the two exterior flat assembly surfaces also has a channel etched thereon, the channel being the mirror image of and in full registration with the channel etched on the adjacent side of an adjacent plate. 